I KNOW MY CRABAPPLES WELL ENOUGH to know that 2 of 10 were not happy this spring at flowering time, and now I know why. My friend Dennis Mareb of Windy Hill Farm in Gt. Barrington, MA, a nurseryman and longtime apple-orchard owner, performed the diagnostics this week: not good. Apple-bark borer has found its way into at least two of the trees, and from the looks of things, they are goners.
Various kinds of borers can impact crabapples, not just the apple-bark borer, I know now after reading the fact sheets from various Cooperative Extensions around the country. Unlike the one in the photo up top, with borer entry points at eye level, one of my trees has damage at the base, more like what you’d expect from a vole, but there’s a tell-tale sign, Dennis explained: the presence of frass, or sawdust-like reddish debris that’s a combination of wood particles and insect wastes. Where you once would have seen cambium, you see frass. Sometimes cracks in the bark will also ooze sap.
If you have a strong stomach and want to see what I am up against, Clemson University and Colorado State have some lovely photos of borers. I would have taken the shots myself had I been able to locate the hideous creatures, but so far no luck. If you are looking for me tomorrow, I will be out there with pieces of wire probing the tunnel system that was once my tree’s infrastructure, to see if I can locate my unwanted roommates.
What could I have done to prevent this? Maybe nothing, as some borers invade even healthy trees, the literature says. But best practices warn to keep the ground at the base of the trees clear of weeds and even turf; to keep trees growing vigorously by providing sufficient moisture and nutrients, especially when they are newly planting or under any other stress; and to keep a watchful eye.
This is not my first borer experience, having lost several of the highly ornamental golden locusts, Robinia pseudoacacia ‘Frisia,’ a few years ago just as they started to shape up into nice trees. It’s always interesting when a creature so small, and unseen, as a borer can fell a thing the size of a tree (not to mention what it does to the gardener’s sense of optimism).